Saturday, February 28, 2009

Readers of a certain vintage will have fond memories of the Turok, Son of Son series from Dell Comics. Apparently Turok and Andar actually started their adventures in Four Color Comics #567 way back in 1954.

Atomic Surgery presents the first half of their first story, explaining just how they ended up in that Lost Valley.

"After over a hundred years of local palaeontological discovery and excavation, the Frenchman Formation Terrestrial Ecosystem Conference will be held in Eastend, Saskatchewan. Attendees from across North America will present research on the wealth of fossils found in southwest Saskatchewan, including Scotty the T. rex. The organizers of this event (the T. rex Discovery Centre, the Royal Saskatchewan Museum, and the University of Alberta) welcome your participation."

Friday, February 27, 2009

Jack Horner has a new book coming out shortly in which he lays out his plan to resurrect a dinosaur. Wired magazine has a Q&A with Jack in its current issue that you can read in its entirety here.

“Flip the right genetic switches in a chicken embryo and you just might hatch a baby dino. Paleontologist Jack Horner intends to do it. He explains his scheme to rewind evolution in a new book, How to Build a Dinosaur: Extinction Doesn't Have to Be Forever. We asked him if there is anything—anything at all—that could possibly go wrong.

Wired: Dinochicken—walk me through the concept.

Jack Horner: Birds are descendants of dinosaurs. They carry their DNA. So in its early stages, a chicken embryo will develop dinosaur traits like a long tail, teeth, and three-fingered hands. If you can find the genes that cancel the tail and fuse the fingers to build a wing—and turn those genes off—you can grow animals with dinosaur characteristics.”

Ancient footprints found at Rutgers' Koobi Fora Field School show that some of the earliest humans walked like us and did so on anatomically modern feet 1.5 million years ago

The footprints were discovered in two 1.5 million-year-old sedimentary layers near Ileret in northern Kenya. These rarest of impressions yielded information about soft tissue form and structure not normally accessible in fossilized bones. The Ileret footprints constitute the oldest evidence of an essentially modern human-like foot anatomy.

The upper sediment layer contained three footprint trails: two trails of two prints each, one of seven prints and a number of isolated prints. Five meters deeper, the other sediment surface preserved one trail of two prints and a single isolated smaller print, probably from a juvenile.

In these specimens, the big toe is parallel to the other toes, unlike that of apes where it is separated in a grasping configuration useful in the trees. The footprints show a pronounced human-like arch and short toes, typically associated with an upright bipedal stance. The size, spacing and depth of the impressions were the basis of estimates of weight, stride and gait, all found to be within the range of modern humans.

Based on size of the footprints and their modern anatomical characteristics, the authors attribute the prints to the hominid Homo ergaster, or early Homo erectus as it is more generally known. This was the first hominid to have had the same body proportions (longer legs and shorter arms) as modern Homo sapiens. Various H. ergaster or H. erectus remains have been found in Tanzania, Ethiopia, Kenya and South Africa, with dates consistent with the Ileret footprints.

Other hominid fossil footprints dating to 3.6 million years ago had been discovered in 1978 by Mary Leakey at Laetoli, Tanzania. These are attributed to the less advanced Australopithecus afarensis, a possible ancestral hominid. The smaller, older Laetoli prints show indications of upright bipedal posture but possess a shallower arch and a more ape-like, divergent big toe. link

A video with some great walking (or at least stomping) in it. It also seems to capture (for me) the essence of the graduate school experience in a ‘Fellini meets Bergman’ sort of way.

Abstract: Stegosaurian dinosaurs have a quadrupedal stance, short forelimbs, short necks, and are generally considered to be low browsers. A new stegosaur, Miragaia longicollum gen. et sp. nov., from the Late Jurassic of Portugal, has a neck comprising at least 17 cervical vertebrae. This is eight additional cervical vertebrae when compared with the ancestral condition seen in basal ornithischians such as Scutellosaurus. Miragaia has a higher cervical count than most of the iconically long-necked sauropod dinosaurs. Long neck length has been achieved by ‘cervicalization’ of anterior dorsal vertebrae and probable lengthening of centra.

All these anatomical features are evolutionarily convergent with those exhibited in the necks of sauropod dinosaurs. Miragaia longicollum is based upon a partial articulated skeleton, and includes the only known cranial remains from any European stegosaur.

A well-resolved phylogeny supports a new clade that unites Miragaia and Dacentrurus as the sister group to Stegosaurus; this new topology challenges the common view of Dacentrurus as a basal stegosaur.

A fossil of the fish Incisoscutum ritchiei from the Upper Devonian period (350 Ma) of the Gogo formation of western Australia contains a 5 cm-long embryo. This specimen is one of the earliest examples of a pregnant vertebrate and shows that internal fertilisation, or sex, started far sooner than previously thought.

The process of internal fertilisation and giving birth to live young, or viviparity, differentiates some fish and mammals from other animals such as reptiles and amphibians. Johanson and her colleagues believe it was the main reproductive method for early fish groups such as the placoderms and could have evolved in other fish groups.

‘Sex was far more common in these primitive prehistoric animals,’ adds Dr Johanson. ‘However, copulation appears to be the main way they reproduced, demonstrating that ‘sex’ started a lot sooner than we thought.’

‘This specimen shows just how important the Museum collections are because knowledge evolves and we have new interpretations that we can apply to fossils in the collections.'link.

Abstract [edit]: Here we report the discovery of embryos in the Arthrodira inside specimens of Incisoscutum ritchiei from the Upper Devonian Gogo Formation of Western Australia (approximately 380 million years ago), providing the first evidence, to our knowledge, for reproduction using internal fertilization in this diverse group. We show that Incisoscutum and some phyllolepid arthrodires possessed pelvic girdles … indicating that the pelvic fin was used in copulation. As homology between similar pelvic girdle skeletal structures in ptyctodontids, arthrodires and chondrichthyans is difficult to reconcile in the light of current phylogenies of lower gnathostomes, we explain these similarities as being most likely due to convergence (homoplasy). These new finds confirm that reproduction by internal fertilization and viviparity was much more widespread in the earliest gnathostomes than had been previously appreciated.

Abstract [edit]: Among the more intriguing deep time co-evolutionary scenarios are those that relate changes in Cretaceous dinosaur faunas to the primary radiation of flowering plants. We have compiled a new database of Cretaceous dinosaur and plant distributions from information in the primary literature. This is used as the basis for plotting taxonomic diversity and occurrence curves for herbivorous dinosaurs (Sauropodomorpha, Stegosauria, Ankylosauria, Ornithopoda, Ceratopsia, Pachycephalosauria and herbivorous theropods) and major groups of plants (angiosperms, Bennettitales, cycads, cycadophytes, conifers, Filicales and Ginkgoales) that co-occur in dinosaur-bearing formations.

Pairwise statistical comparisons were made between various floral and faunal groups to test for any significant similarities in the shapes of their diversity curves through time. We show that, with one possible exception, diversity patterns for major groups of herbivorous dinosaurs are not positively correlated with angiosperm diversity.

The diversification of Late Cretaceous pachycephalosaurs (excluding the problematic taxon Stenopelix) shows a positive correlation, but this might be spuriously related to poor sampling in the Turonian–Santonian interval. Stegosauria shows a significant negative correlation with flowering plants and a significant positive correlation with the nonflowering cycadophytes (cycads, Bennettitales). This interesting pattern is worthy of further investigation, and it reflects the decline of both stegosaurs and cycadophytes during the Early Cretaceous.

Sunday, February 22, 2009

I haven’t linked to Steve Bissette’s blog in a while, but this recent posting by Steve made me sit up and take notice. Here’s Steve:

“Cayetano “Cat” Garza and I just finished up a cover art gig for our good friends at Blackcoat Press. We collaborated on the color cover art for the upcoming translation of the never-before-published-in- English 1910 French science-fiction novel, Panic in Paris.

Dinosaurs erupt from beneath the streets of Paris, two years before Sir Arthur Conan Doyle’s classic The Lost World was published (ending with Professor Challenger and his expedition bringing pterodactyls to London for the final chapter) — meaning this is an essential new discovery and addition to the history of paleontological science fiction, and perhaps even the first full-blown entry in the venerable ‘monsters attack metropolis’ genre of giant monster fantasy.”

The emergence of the ribosome constituted a pivotal step in the evolution of life. This event happened nearly four billion years ago, and any traces of early stages of ribosome evolution are generally thought to have completely eroded away. Surprisingly, a detailed analysis of the structure of the modern ribosome reveals a concerted and modular scheme of its early evolution.

The key breakthrough came when they realized that the ribosome is organized by a set of simple structural rules and that it had to be assembled from basic building blocks in a very specific order; otherwise it would have fallen apart. They then mathematically showed that the construction of the ribosome likely followed an ordered series of steps to form the structure found in the first living cell. To this day, that structure exists almost unchanged in our own cells.

"Thanks to the research of Sergey Steinberg and Konstantin Bokov, scientists now have a glimpse of one key event that emerged spontaneously out of the primordial chemical soup of the early Earth," explains Stephen Michnick. link

Friday, February 20, 2009

Reptilicus (1961), has been described as the “Plan 9 from Outer Space” of giant monster movies and really has to be seen to be believed. It's the grand prize winner in the contest for “poster that is waaay better than the movie” – that wonderous art is by Reynold Brown, by the way.

Thursday, February 19, 2009

Study takes new look at skeletal system of pterosaurs and their modern relatives

A new study scientists explain how balloon-like air sacs, which extended from the lungs to inside the skeleton of pterosaurs, provided an efficient breathing system for the ancient beasts. The system reduced the density of the body in pterosaurs, which in turn allowed for the evolution of the largest flying vertebrates.

"We offer a reconstruction of the breathing system in pterosaurs, one that proposes the existence of a mechanism with the same essential structure to that of modern birds — except 70 million years earlier," said study co-author Leon Claessens.

Because fossils rarely preserve soft tissues, the research team conducted a comparative study that included pterosaurs, birds and crocodilians in order to get a better understanding of the relationships among air sacs, lung structure and the skeleton. By using X-ray movies and CT scans, the group characterized how the skeleton works to move air through the lungs in living animals, and also how to identify the signature traces left on bones that have been invaded by air sacs.

The evolution of pneumaticity in pteroaurs

Not only do the extinct pterosaurs show evidence that their bones that were invaded by air sacs, but patterns of pneumaticity throughout the entire skeleton of different pterosaur species parallel trends identified in many living bird groups. For example, there is a direct relationship between the proportion of the skeleton invaded by air sacs and the absolute body size of an animal.

Matthew was a superb mammalian paleontologist and important biogeographic theorist, and also G. G. Simpson's primary mentor. Matthew published voluminiously on the fossil record of mammals and advocated a fully modern approach to taxonomy that emphasized tying scientific names to natural biological populations. His 1930 paper gives a clear statement of this position.

Matthew's key biogeographic theory was that waves of faunal migration repeatedly went from the northern continents southwards. This theory, which had obvious racial and political overtones, was justified by a "stabilist" view of paleogeography (i.e., that the continents had never moved from their modern positions), and by evidence from the relatively young fossil record of mammals, at the expense of other data that would have shown the more ancient interconnections among South America, Africa, India, and Australia. Remarkably, Matthew remained a Darwinian despite working for the autocratic orthogeneticist H. F. Osborn for three decades.

Hedin was a Swedish explorer and geographer, born in Stockholm, who led four multi-year expeditions into Central Asia between 1897 and 1935. Although not as well known as Roy Chapman Andrews his work in the regions revealed a wealth of cultural, archaeological and palaeontological wonders.

During his first major Asian expedition, he crossed the Pamirs, charted Lop Nor (Lake) in China, and finally arrived at Beijing. He then journeyed to Tibet by way of Mongolia, Siberia, and the Gobi Desert. Hedin explored Tibet and Xinjiang (Sinkiang), identified the sources of the Brahmaputra, Indus, and Sutlej rivers, and, in 1906, explored and named the Trans-Himalayas. In 1927 Hedin led an expedition of Chinese and Swedish scientists into Central Asia.

Directed by Howard Hawks in 1938,Grant plays paleontologist David Huxley who is trying to secure a $1,000,000.00 endowment for his museum. He meets up with Hepburn’s seemingly scatterbrained heiress, Susan Vance, who becomes determined to derail Grant’s next day wedding. Over the course of the next 24 hours Grant gets completely mired in Hepburn’s whirlwind ad hoc plans to catch her new (and completely reluctant) beau that includes hunting for her leopard (the ‘Baby’ of the title), having her steal his clothes, ending up in jail, falling in a stream, and finally losing his “intercostal clavicle” to Hepburn’s dog that was to be the final element needed complete the Brontosaurus skeleton he’s been working on for four years.

In the end they end up in each others arms but suspended over the destroyed skeleton. The fast-paced, witty script, sharp direction and comedic chemistry between Grant and Hepburn all combine to make this film worthy of multiple repeat viewings.

Note: The Palaeoblogger is sick this week. Things should return to normal in a few days

The 3.2-million-year-old bones of 'Lucy', the skeleton of the Australopithecus afarensis hominin discovered in Ethiopia in 1974, have undergone a complete high-resolution computed tomography scan. Researchers at the University of Texas at Austin have thereby created a digitized record that will allow the bones' internal structure to be examined (pictured below).

But interest from US museums in hosting an exhibition featuring the 40% complete skeleton is lagging, and officials say it will go into indefinite storage next month at the Houston Museum of Natural Science in Texas.

A $2.25-million, five-month Lucy exhibition at the Pacific Science Center in Seattle, Washington, which closes on 8 March, is the second leg of what was originally planned to be a ten-city, six-year tour, although concerns were raised over the effects the tour would have on the delicate fossil (see Nature 444, 8; 2006). But total attendance at the Seattle exhibition is likely to be a third of the 250,000 projected, and no other museum has yet signed up for the exhibition.

Keenly observing nature in all its forms—from fossil sloths to mockingbirds, primroses to children—Darwin saw that we all are related.Every living thing shares an ancestry, he concluded, and the vast diversity of life on Earth results from processes at work over millions of years and still at work today. Darwin's explanation for this great unfolding of life through time—the theory of evolution by natural selection—transformed our understanding of the living world, much as the ideas of Galileo, Newton and Einstein revolutionized our understanding of the physical universe.

Darwin's theory of evolution by natural selection underlies all modern biology. It enables us to decipher our genes and fight viruses, and to understand Earth's fossil record and rich biodiversity. Simple yet at times controversial, misunderstood and misused for social goals, the theory remains unchallenged as the central concept of biology. Charles Darwin, reluctant revolutionary, profoundly altered our view of the natural world and our place in it.

The greatest dinosaur hunter of the twentieth century was Barnum Brown, who began his career at the American Museum of Natural History in 1897 as an assistant to Henry Fairfield Osborn. Brown traveled all over the world collecting dinosaurs and fossil mammals. Some consider him to be the last of the great dinosaur hunters.

Brown was always impeccably dressed, often wearing a tie and topcoat even in the field. He was a shrewd "horse trader" when it came to wheeling and dealing for fossil specimens. Many of Brown's greatest discoveries, including the first specimens of Tyrannosaurus rex ever found, are displayed in the Museum's Dinosaur Halls.

The extinct Pyrenean ibex has been resurrected by cloning for the first time—though the clone died minutes after birth. Scientists used the frozen skin in 2003 to clone the bucardo, a subspecies of Spanish ibex that went extinct in 2000.

Tuesday, February 10, 2009

Schematic drawing (lateral view) of the generalized cichlid cranial skeleton, showing the relative location of the oral jaws (purple) and the pharyngeal jaws of PA7 (blue)

Scientists report that a common gene regulatory circuit controls the development of all dentitions, from the first teeth in the throats of jawless fishes that lived half a billion years ago, to the incisors and molars of modern vertebrates.

"It's likely that every tooth made throughout the evolution of vertebrates has used this core set of genes," said Gareth Fraser.

The first vertebrates to have teeth were a group of eel-like jawless fish known as the conodonts that had teeth not in their mouth, but lining the throat. This particular group is long since extinct, but some modern fish retain teeth in the throat (pharynx). Dr. Fraser and colleagues studied tooth formation in a group of fish known for their rapid rate of evolution, the cichlids of Africa's Lake Malawi. The cichlids have teeth both in their oral jaws, like humans, and deep in their throats on a pharyngeal jaw. A co-author of the paper, Darrin Hulsey, first identified a surprising positive correlation between the number of teeth in the oral jaw and in the throat in these fish.

The Coevolutionary History of Jaws and Dentitions. Full caption HERECLICK TO ENLARGE

"Originally, I thought there wouldn't be a correlation due to the developmental differences and the evolutionary distinction between the two jaw regions, but it turns out there is," explained Fraser. "So fish that have fewer oral teeth also have fewer pharyngeal teeth. This shows that on some level there's a genetic control that governs the number of teeth in both regions."

The team investigated what this control might be by using a technique localizing gene expression in the cells during tooth development, known as in situ hybridization, and found that a common genetic network governs teeth in the two locations. link

In 1667, a classic paleontological paper by Nicolaus Steno was published by the Royal Society, London. His topic, Head of a shark dissected, represented the first such scientific paper to recognise that fossils were the remains of creatures who had died and subsequently had become petrified. Controversy resulted as the same claim had been made in the time of the ancient Greeks, two millennia earlier.

Belated Happy Birthday to this blog that turned 4 years old last Sunday, with more than 1800 postings since we started.

Monday, February 09, 2009

The University of Alaska Museum of the North has unveiled what officials call one of the largest, oldest and northernmost marine reptile fossils ever found.

Officials say the fossil sat in the Brooks Range for almost 210 million years before it was discovered in 1950, eventually arriving in Fairbanks.

Discovered by geologist Bud Ken and Carl Benson while mapping rocks in the foothills of the Brooks Range along Cutaway Creek, 200 miles south of Point Barrow, it waited another 50 years to be collected.

The fossil sat in museum storage for five years before it was rediscovered by our old friend, Dr. Patrick Druckenmiller (above), the Earth sciences curator for Museum of the North, who has been cleaning and studying the fossilized marine reptile over the past year. link.

The UK Newspaper, The Guardian, has a nice web site devoted to dinosaurs. Each single web page features a colour illustration and information about a specific dinosaur or answers a question about them. It’s a great resource for kids, and adults will learn a few new things as well.

Sunday, February 08, 2009

In 1865, Gregor Mendel, who first discovered the laws of genetics, read his first scientific paper to the Brünn Society for the study of Natural Sciences in Moravia (published 1866).

He described his investigations with pea plants. Although he sent 40 reprints of his article to prominent biologists throughout Europe, including Darwin, only one was interested enough to reply.

Most of the reprints, including Darwin’s, were discovered later with the pages uncut, meaning they were never read.

Fortunately, 18 years after Mendel's death, three botanists in three different countries researching the laws of inheritance, in spring 1900, came to realize that Mendel had found them first. Mendel was finally acknowledged as a pioneer in the field which became known as genetics.Info from Today In Science History

A missing link in the evolution of the front claw of living scorpions and horseshoe crabs was identified with the discovery of a 390 million-year-old fossil, Schinderhannes bartelsi.

With a head like the giant Cambrian aquatic predator Anomalocaris and a body like a modern arthropod, the specimen (below) is the only known example of this unusual creature. The fossil's head section has large bulbous eyes, a circular mouth opening and a pair of segmented, opposable appendages with spines projecting inward along their length. The trunk section is made up of 12 segments, each with small appendages, and a long tail spine. Between the head and trunk, there is a pair of large triangular wing-like limbs — that likely propelled the creature like a swimming penguin. Unlike its ancestors from the Cambrian period, which reached three feet in length, Schinderhannes is only about 4 inches long.

Steinmann Institute/University of Bonn

Scientists have puzzled over the origins of the paired grasping appendages found on the heads of scorpions and horseshoe crabs. The researchers suggest that Schinderhannes gives a hint. Their appendages may be an equivalent to those found in the ancient predatory ancestor, Anomalocaris — even though creatures with those head structures were thought to have become extinct by the middle of the Cambrian Period, 100 million years before Schinderhannes lived.

Scientists quantified the time of origin for 711 lineages of bivalves living in the oceans today, and converted them to evolutionary origination rates. In all but the highest-latitude locations, the team saw the clear signs of a strong increase in origination rates following the end of the Cretaceous.

Abstract: The long-term effects of mass extinctions on spatial and evolutionary dynamics have been poorly studied. Here we show that the evolutionary consequences of the end-Cretaceous [Cretaceous/Paleogene (K/Pg)] mass extinction persist in present-day biogeography. The geologic ages of genera of living marine bivalves show a significant break from a smooth exponential distribution, corresponding to the K/Pg boundary. The break reflects a permanent increase in origination rates, intermediate between the Mesozoic rate and the post-extinction recovery pulse. This global rate shift is most clearly seen today in tropical bioprovinces and weakens toward the poles.

Coupled with the modern geographic distributions of taxa originating before and after the K/Pg boundary, this spatial pattern indicates that tropical origination rates after the K/Pg event have left a permanent mark on the taxonomic and biogeographic structure of the modern biota, despite the complex Cenozoic history of marine environments.

Mary Douglas Nicol Leakey was in London, England. She meet her future husband, Louis Leakey, when he asked her to illustrate his book, 'Adam’s Ancestors'. Mary and Louis spent from 1935 to 1959 at Olduvai Gorge in the Serengeti Plains of northern Tanzania where they worked to reconstruct many Stone Age cultures dating as far back as 100,000 to two million years ago. They documented stone tools from primitive stone-chopping instruments to multi-purpose hand axes.

In October of 1947, while on Rusinga Island, Mary unearthed a Proconsul africanus skull, the first skull of a fossil ape ever to be found. It was dated to be twenty million years old. An Australopithecus boisei skull was uncovered in 1959. Not long afterwards, a less robust Homo habilis was found. In 1965 the duo uncovered a Homo erectus cranium.

After her husband died in 1972, Mary continued her work at Olduvai and Laetoli. She discovered Homo fossils at Laetoli which were more than 3.75 million years old, fifteen new species and one new genus. From 1978-81 Mary and her staff worked to uncover the Laetoli hominid footprint trail which was left in volcanic ashes 3.6 million years ago.

Scientists have found the oldest evidence for animals in the fossil record.

The researchers examined sedimentary rocks in south Oman, and found an anomalously high amount of distinctive steroids are produced by sponges that date back to 635 million years ago, to around the end of the last immense ice age.

The researchers argue that the discovery of the sponges is evidence for multicellular animal life beginning 100 million years before the Cambrian explosion that began about 530 million years.

According to Gordon Love, the climatic shock of the extensive glacial episodes of the Neoproterozoic era (1000-542 million years ago) likely caused a major reorganization of marine ecosystems, perhaps by irrevocably altering ocean chemistry."This paved the way for the evolution of animal feeders living on the seafloor," he said. "We believe we are converging on the correct date for the divergence of complex multicellular animal life, on the shallow ocean floor between 635 and 750 million years ago."

The steroids that Love and his colleagues observed in the Omani rocks are essential biochemicals present in the cell membranes of the sponges, and help provide the membranes with structural support. The sponges are a few millimeters in size, immobile, and were filter feeders existing on the seafloor. link

Brongniart was a French mineralogist, geologist, and naturalist, who first arranged the geologic formations of the Tertiary Period (from 66.4 to 1.6 million years ago) in chronological order and described them.

He made the first systematic study of trilobites that became important in determining the chronology of Paleozoic strata (from 540 to 245 million years ago).

He helped introduce the principle of geologic dating by the identification of distinctive fossils found in each stratum and noted that the Paris formations had been created under alternate freshwater and saltwater conditions. image. From Today In Science History

Wednesday, February 04, 2009

Scientists have recovered fossils from a new 60-million-year-old South American snake, Titanoboa cerrejonensi. The size of its vertebrae suggest it weighed 1,140 kg and measured 13 m (42.7 feet) nose to tail tip. link

Compressive stress in the cranium of Australopithecus africanus, an extinct early human, imposed by biting on the premolar teeth. Bright colors correspond to high stresses, and indicate that a bony pillar running alongside the opening of the nasal cavity acts as a strut that structurally reinforces the face against premolar loads.

New research reveals nut-cracking abilities in our 2.5-million-year-old relatives that enabled them to alter their diet to adapt to changes in food sources in their environment.

Using state-of-the-art computer modeling and simulation technology – the same kind engineers use to simulate how a car reacts to forces in a front-end collision – evolutionary scientists built a virtual model of the A. africanus skull and were able to see just how the jaw operated and what forces it could produce.

"We started with a CT scan of a skull that is one of the most complete specimens of A. africanus that we have," said Mark Spencer, researcher in ASU's Institute of Human Origins and a lead investigator on the project. This would be a later ancestor of Lucy – STS5 - who is affectionately known as "Mrs. Ples." The skull, discovered in 1947, has struts on the side of the nose, but no teeth. "We meshed those data with another specimen with teeth to make the virtual model of the bone and tooth structure.

"Then we looked at chimpanzees, who share common features with Australopithecus, and took measurements of how their muscles work and added that to the model. We were able to validate this model by comparing it to a similar model built for a species of monkey called macaques," Spencer explained.

The result illustrates forces absorbed by the cranial structure in simulated bite scenarios and how their unusual facial features were ideally suited to support the heavy loads of cracking hard nuts.

"This reinforces the body of research indicating that facial specializations in species of early humans are adaptations due to a specialized diet," said Spencer. "The enlargement of the premolars, the heavy tooth enamel and the evidence now that they were loading forcefully on the molars suggest the size of the objects were larger than the previously hypothesized small seeds and nuts. link

Fossils of female Maiacetus inuus with near-term fetus in utero, as found in the field. The female's skull is shaded white (teeth brown), and other parts of her skeleton are shaded red. The single fetus, in birth position inside the mother whale, is shaded blue (teeth orange).UMMNH

Two newly described fossil whales---a pregnant female and a male of the same species--reveal how primitive whales gave birth and provide new insights into how whales made the transition from land to sea.

The 47.5 million-year-old fossils, discovered in Pakistan in 2000 and 2004, are the first discovery of a fetal skeleton of an extinct whale in the group known as Archaeoceti, and the find represents a new species dubbed Maiacetus inuus. (Maiacetus means "mother whale," and Inuus was a Roman fertility god.) The fetus is positioned for head-first delivery, like land mammals but unlike modern whales, indicating that these whales still gave birth on land.

Another clue to the whales' lifestyle is the well-developed set of teeth in the fetus, suggesting that Maiacetus newborns were equipped to fend for themselves, rather than being helpless in early life.

Male Maiacetus inuus. John Klausmeyer & Bonnie Miljour/UMMNH

The 8.5-foot-long male specimen, collected four years later from the same fossil beds, shares characteristic anatomical features with the female of the species, but its virtually complete skeleton is 12 percent larger overall, and its canine teeth or fangs 20 percent larger. Such size discrepancies are not uncommon among whales and their kin; in some species the females are larger, while in others the males are slightly to considerably bigger. The size difference of male and female Maiacetus is only moderate, hinting that the males didn't control territories or command harems of females.

Like other primitive archaeocetes, Maiacetus had four legs modified for foot-powered swimming, and although these whales could support their weight on their flipper-like limbs, they probably couldn't travel far on land.

"They clearly were tied to the shore," Gingerich said. "They were living at the land-sea interface and going back and forth."

Tuesday, February 03, 2009

Mantell, a physician of Lewes in Sussex in southern England, had for years been collecting fossils in the sandstone of Tilgate forest, and he had discovered bones belonging to three extinct species: a giant crocodile, a plesiosaur, and Buckland's Megalosaurus. But in 1822 he found several teeth that "possessed characters so remarkable" that they had to have come from a fourth and distinct species of Saurian. After consulting numerous experts, Mantell finally recognized that the teeth bore an uncanny resemblance to the teeth of the living iguana, except that they were twenty times larger. In this paper, the second published description of a dinosaur, he concluded that he had found the teeth of a giant lizard, which he named Iguanodon, or "Iguana-tooth."

Mantell illustrated his announcement with a single lithographed plate. Mantell included at the bottom of the plate a drawing of a recent iguana jaw, which is shown four times natural size, and for further comparison, he added views of the inner and outer surface of a single iguana tooth, "greatly magnified."

The traditional story that Mantell's wife found the first teeth in 1822, while the doctor was visiting a patient, appears, alas, to be unfounded.

Any student of biology, or anyone with an interest in the natural world, will be familiar with Ernst Mayr who passed away on February 3rd in Bedford, Mass. Born in Kempton, Germany he joined the American Museum of Natural History as a curator in 1931. In 1953 he left the museum to work at Harvard University where he stayed until his retirement in 1975.

While working on the problem of speciation in the birds of New Guinea, Mayr realized that the multitude of species and and subspecies that he saw could best be explained as being a snapshot of evolution in action. He suggested that new species could arise when the range of one species was fractured long enough for members in different parts of the range to evolve characters that would not allow individuals to reproduce when they were brought back together again. This lead to him developing the “biological species concept” in which species are defined as populations of interbreeding organisms rather than just a collection of characters. This idea, along with his theory of “allopatric speciation” was published in his book “Systematics and the Origin of the Species” (1942) and later contributed to the “Punctuated Equilibrium” theory of Niles Eldredge and Stephen Jay Gould.

Ernst Mayr was himself inspired by the work of geneticist Theodosius Dobzhansky on the fruit fly Drosophila melanogaster and his book “Genetics and the Origin of the Species” (1937). These two men, together with the paleontologist George Gaylord Simpson, combined the sciences of genetics, zoology and paleontology into what is now known as “the new synthesis” that provides the modern experimental underpinning to the concepts that Charles Darwin presented in his book, “On the Origin of the Species” .

For anyone interested in learning more about modern evolutionary theory I’d recommend Mayr’s recent book “What Evolution Is” (2002). It’s written in an engaging and readable format from the perspective of someone who’s thought about evolution all his life.